When manipulating integrated circuits and other electronic devices, an automated device handler is commonly used to pick up the device at one location and place it at another location for processing, marking, storage, etc. The handler comprises a positioning mechanism that is moved by an actuator. The positioning mechanism picks up the device with a chuck or a gripper that may rotate about the vertical axis of the handler. The rotation of the chuck combined with the movement of the positioning mechanism enables the handler to pick up and deliver a device to any location, in any orientation, within the working space of the handler.
Devices are often marked to indicate to the user how that particular device was processed. For example, a programmable read-only memory ("PROM") may be marked with indicia to identify a program or data stored in the PROM. After being processed, the device is picked up by the chuck on the handler's positioning mechanism and is delivered to the marker. The marker comprises a marker, such as a laser marking head, and a support mechanism where the device is held during marking. The device is placed onto the support mechanism, marked by the laser, then picked up by the positioning mechanism and delivered to a storage location for devices that have been processed.
FIGS. 1A-1E are schematic diagrams indicating the steps involved in marking devices according to the prior art. In FIG. 1A, a device 2a is being marked by a marker 4, such as a laser. The device 2a is supported by a chuck 6a which is rigidly mounted on a turntable 8. A number of chucks 6 are positioned about the perimeter of the turntable 8, with each chuck 6 oriented vertically to position the devices 2 for marking. The chucks 6 are each essentially conduits of a resilient material that are open ended. The conduits are coupled to a vacuum source so that the devices 2 are securely held on the chucks 6 by suction. Other types of chucks may alternatively be used. The marker 4 is positioned directly above the turntable 8, and is aimed downward at the device 2a. While one device 2a is being marked, a second device 2b is engaged with the chuck 6b adjacent the chuck 6a in the marking position. Thus, once the first device 2a is marked, the turntable 8 can rotate, moving the adjacent device 2b into the marking position.
During the marking process, a positioning mechanism 10 picks up yet another device 2c from a first storage location 12. The positioning mechanism 10 has a positioning chuck 11 at one end that is adapted to engage and then pick up devices 2 such as integrated circuits. The positioning mechanism 10 is also positioned in a vertical orientation. This orientation allows the positioning mechanism 10 to properly place the device 2c in the chuck 6c on the turntable 8, as well as to properly remove the device 2c therefrom.
As shown in FIG. 1B, the turntable 8 has rotated so that the device 2b is at the marking position, and the positioning mechanism 10 is placing an unmarked device 2c on the next available chuck 6c. After each device 2 is marked, the turntable rotates to position the next chuck 6 into the proper position for marking the next device 2.
After being marked, the device 2a is picked up by the positioning mechanism 10 and delivered to a second storage location 14, as shown in FIGS. 1C and 1D. After the positioning mechanism 10 places the device 2a in the second storage location 14, the positioning mechanism 10 returns to the first storage location 12 in order to pick up another unmarked device 2d, as shown in FIG. 1E. At this point, the above-described process starts over.
Because the positioning mechanism 10 and the marker 4 are both oriented above the device 2 being marked, simultaneous operation of the positioning mechanism 10 and the marker 4 requires that the chucks 6 on the turntable 8 be spaced apart far enough to prevent interference between the positioning mechanism 10 and the marker 4. To account for this, the size of the turntable 8 must be quite large, thereby making any device incorporating such a system large as well.
Another problem with the prior art system shown in FIGS. 1A-E is caused by the upwardly facing orientation of the chucks 6. More specifically, the chucks 6 face upwardly so that any dust generated during the marking process can be drawn into the chucks, thus creating additional costs associated with cleaning the system and possibly damaging it.
Yet another problem with the prior art system shown in FIGS. 1A-E is caused by the downwardly facing orientation of the processor. For example, where the processor is a laser marker oriented directly above the device, smoke rising from the face of the device 2 being marked can soil the laser's lens, adversely affecting the laser's performance and creating additional costs associated with cleaning the lens.
A need therefore exists for an improved method and apparatus for retaining devices during processing.